John Bolton, Donald Trump's former national security adviser, has pleaded not guilty to charges of mishandling classified information.

The 18 charges stem from allegations he shared or retained sensitive materials, including some characterized as top secret. He entered the plea after surrendering to authorities at a federal court hearing on Friday.

Bolton served during Trump's first administration but parted with the White House contentiously, and has become one of the president's most vocal public critics.

The indictment makes Bolton, 76, the third of the US president's political opponents to face charges in recent weeks. Bolton has said he would defend his lawful conduct.

Bolton, wearing a dark blue suit and maroon tie, did not speak with reporters as he arrived at the courthouse in Greenbelt, Maryland. Not guilty, your honor, Bolton, 76, said in court. He was released on his own recognizance and a hearing in the case is scheduled for 21 November.

Prosecutors have accused Bolton of using personal messaging apps and email to illegally transmit sensitive information. These documents revealed intelligence about future attacks, foreign adversaries, and foreign-policy relations, prosecutors wrote.

Bolton stated that he has become the latest target of the Justice Department's alleged politicization, articulating that charges against him have been distorted or denied in the past.

The indictment issue alleges Bolton shared diary-like entries with two unnamed individuals, using his personal email account for messages containing sensitive materials. It also suggests that between 2019 and 2021, Bolton faced a hacking incident believed to be linked to Iran, which may have accessed classified documents.

Defense Attorney Abbe Lowell commented on the case, stating that keeping diaries is not a crime and presented records that he claims are unclassified and were only shared with Bolton's immediate family.

The indictment does not arise in isolation; Bolton has faced scrutiny for his handling of classified information since he published a controversial book regarding his time in Trump's White House, which led to an investigation that concluded without charges.

Trump has publicly attacked Bolton on multiple occasions, depicting him as disloyal and a criminal. The recent political climate intensifies as this indictment follows similar charges against other former Trump administration figures and political opponents.